MBR (Membrane Bioreactor)

A membrane bioreactor (MBR) combines biological wastewater treatment and ultrafiltration membrane separation in a single integrated system. Mixed liquor from the biological reactor passes through submerged or external hollow-fibre ultrafiltration membranes, producing a clarified permeate of consistently high quality. The membrane replaces the secondary clarifier of conventional activated sludge systems, providing an absolute physical barrier that retains biomass and removes suspended solids and pathogens from the treated water regardless of biological settling characteristics.

Conventional activated sludge relies on gravity settling in a secondary clarifier to separate treated water from biological sludge. Settling performance is variable and dependent on sludge settling characteristics, which can deteriorate under high loading or adverse conditions. MBR replaces the clarifier with ultrafiltration membranes, providing an absolute separation barrier that produces consistently high-quality permeate with turbidity below 1 NTU and TSS below 5 mg/L regardless of biological conditions. MBR also operates at higher mixed liquor concentrations, allowing a smaller biological reactor volume and a significantly more compact overall footprint.

MBR permeate consistently achieves turbidity below 1 NTU, suspended solids below 5 mg/L, BOD below 5 mg/L and COD below 30 mg/L. The ultrafiltration membrane provides greater than 4 log removal of bacteria and greater than 3 log removal of viruses, making MBR effluent suitable for direct reuse in non-potable applications or as feed to downstream RO for advanced reuse or indirect potable reuse applications following UV or chlorine disinfection.

MBR produces reuse-grade effluent quality directly from the biological treatment stage without the need for additional tertiary filtration such as sand filtration or cloth media filtration. The consistent membrane barrier ensures effluent quality is maintained during peak loading, biological upsets or variable influent conditions that can cause secondary clarifier performance deterioration. MBR effluent is ready for direct UV or chlorine disinfection and reuse, or as pre-treated feed for RO where higher reuse quality is required, reducing the overall treatment train complexity and footprint.

MBR membrane fouling is managed through a combination of continuous coarse bubble aeration scouring across the membrane surface, periodic relaxation cycles where permeate extraction is paused to allow fouling to be released, and regular chemically enhanced backwash (CEB) sequences using dilute sodium hypochlorite and citric acid solutions. Periodic recovery cleans with stronger chemical solutions restore membrane permeability when routine maintenance is insufficient. All cleaning sequences are automated within the PLC control system and scheduled based on transmembrane pressure trends.

With correct operation, appropriate aeration scouring, regular CEB maintenance and protection from chemical or physical damage, MBR membrane modules typically achieve service lives of 7 to 10 years. Membrane life depends on mixed liquor characteristics, operating flux, cleaning frequency and chemical compatibility. IWTE supplies genuine replacement MBR membrane modules and provides membrane condition monitoring, replacement scheduling and spare parts supply through its service and maintenance programme.

Yes. MBR technology is particularly well suited to containerised and packaged plant configurations due to its compact footprint and self-contained process design. IWTE supplies factory-assembled containerised MBR package plants for remote communities, construction camps, hotels and resorts, military bases and any application where site construction must be minimised. Containerised MBR units are delivered pre-assembled and tested, requiring only connection to inlet, outlet and power supply services at the installation site.

Yes. IWTE provides complete MBR system design and supply encompassing biological process design, reactor sizing, aeration system design, membrane module selection and arrangement, sludge management, PLC and SCADA control, effluent quality monitoring, civil design coordination and commissioning. The entire system is engineered as an integrated scope with a single point of responsibility for performance. IWTE also provides operator training, membrane maintenance protocols and ongoing service support for all MBR systems we supply.